T cells expressing an invariant TCR alpha chain and NK cell markers are expected to exhibit unique functions. Whereas much attention has been paid to CD1d-restricted NKT cells, a second NKT cell population bearing an invariant AV19-AJ33 TCR has recently been identified in mice and humans. Selection and/or expansion of this population require B cells, and would involve a non-classical class I-related molecule MR1. Although their preferential distribution in the gut mucosa indicates their role in the host response at the site of pathogen entry, it remains unknown whether they play an alternative role at different sites or in immunological disorders. Using single-strand conformation polymorphism clonotype analysis, we investigated the presence of the human AV19-AJ33 T cells (V(alpha)7.2-J(alpha)33 T cells) in autopsy samples from multiple sclerosis (MS) patients as well as in nerve biopsy samples from chronic inflammatory demyelinating polyneuropathy (CIDP) patients. Here we report that the V(alpha)7.2-J(alpha)33 T cells are accumulated in some of the central nervous system lesions of MS and in the majority of the peripheral nerve samples from CIDP. We have previously revealed that CD1d-restricted, V(alpha)24-J(alpha)Q NKT cells are remarkably reduced in the peripheral blood from MS. However, V(alpha)7.2-J(alpha)33 T cells are not reduced in the peripheral blood from MS and could be detected in a large majority of the cerebrospinal fluid samples obtained during relapse of MS. The present results indicate that the V(alpha)7.2-J(alpha)33 T cells are involved in the autoimmune inflammatory lesions.